liblzma: Try to use SHA-256 from the operating system.

If the operating system libc or other base libraries
provide SHA-256, use that instead of our own copy.
Note that this doesn't use OpenSSL or libgcrypt or
such libraries to avoid creating dependencies to
other packages.

This supports at least FreeBSD, NetBSD, OpenBSD, Solaris,
MINIX, and Darwin. They all provide similar but not
identical SHA-256 APIs; everyone is a little different.

Thanks to Wim Lewis for the original patch, improvements,
and testing.

2 files changed, 77 insertions, 8 deletions

diff --git a/src/liblzma/check/Makefile.inc b/src/liblzma/check/Makefile.inc
index e4067a9c..dc011a3f 100644
--- a/src/liblzma/check/Makefile.inc
+++ b/src/liblzma/check/Makefile.inc
@@ -47,5 +47,7 @@ endif
 endif
 
 if COND_CHECK_SHA256
+if COND_INTERNAL_SHA256
 liblzma_la_SOURCES += check/sha256.c
 endif
+endif
diff --git a/src/liblzma/check/check.h b/src/liblzma/check/check.h
index e100d2b8..0f96f65b 100644
--- a/src/liblzma/check/check.h
+++ b/src/liblzma/check/check.h
@@ -15,6 +15,43 @@
 
 #include "common.h"
 
+#if defined(HAVE_COMMONCRYPTO_COMMONDIGEST_H)
+#	include <CommonCrypto/CommonDigest.h>
+#elif defined(HAVE_SHA256_H)
+#	include <sys/types.h>
+#	include <sha256.h>
+#elif defined(HAVE_SHA2_H)
+#	include <sys/types.h>
+#	include <sha2.h>
+#elif defined(HAVE_MINIX_SHA2_H)
+#	include <sys/types.h>
+#	include <minix/sha2.h>
+#endif
+
+#if defined(HAVE_CC_SHA256_CTX)
+typedef CC_SHA256_CTX lzma_sha256_state;
+#elif defined(HAVE_SHA256_CTX)
+typedef SHA256_CTX lzma_sha256_state;
+#elif defined(HAVE_SHA2_CTX)
+typedef SHA2_CTX lzma_sha256_state;
+#else
+/// State for the internal SHA-256 implementation
+typedef struct {
+	/// Internal state
+	uint32_t state[8];
+
+	/// Size of the message excluding padding
+	uint64_t size;
+} lzma_sha256_state;
+#endif
+
+#if defined(HAVE_CC_SHA256_INIT)
+#	define LZMA_SHA256FUNC(x) CC_SHA256_ ## x
+#elif defined(HAVE_SHA256_INIT)
+#	define LZMA_SHA256FUNC(x) SHA256_ ## x
+#elif defined(HAVE_SHA256INIT)
+#	define LZMA_SHA256FUNC(x) SHA256 ## x
+#endif
 
 // Index hashing needs the best possible hash function (preferably
 // a cryptographic hash) for maximum reliability.
@@ -43,14 +80,7 @@ typedef struct {
 	union {
 		uint32_t crc32;
 		uint64_t crc64;
-
-		struct {
-			/// Internal state
-			uint32_t state[8];
-
-			/// Size of the message excluding padding
-			uint64_t size;
-		} sha256;
+		lzma_sha256_state sha256;
 	} state;
 
 } lzma_check_state;
@@ -82,6 +112,8 @@ extern void lzma_check_update(lzma_check_state *check, lzma_check type,
 extern void lzma_check_finish(lzma_check_state *check, lzma_check type);
 
 
+#ifndef LZMA_SHA256FUNC
+
 /// Prepare SHA-256 state for new input.
 extern void lzma_sha256_init(lzma_check_state *check);
 
@@ -92,4 +124,39 @@ extern void lzma_sha256_update(
 /// Finish the SHA-256 calculation and store the result to check->buffer.u8.
 extern void lzma_sha256_finish(lzma_check_state *check);
 
+
+#else
+
+static inline void
+lzma_sha256_init(lzma_check_state *check)
+{
+	LZMA_SHA256FUNC(Init)(&check->state.sha256);
+}
+
+
+static inline void
+lzma_sha256_update(const uint8_t *buf, size_t size, lzma_check_state *check)
+{
+#if defined(HAVE_CC_SHA256_INIT) && SIZE_MAX > UINT32_MAX
+	// Darwin's CC_SHA256_Update takes uint32_t as the buffer size,
+	// so use a loop to support size_t.
+	while (size > UINT32_MAX) {
+		LZMA_SHA256FUNC(Update)(&check->state.sha256, buf, UINT32_MAX);
+		buf += UINT32_MAX;
+		size -= UINT32_MAX;
+	}
+#endif
+
+	LZMA_SHA256FUNC(Update)(&check->state.sha256, buf, size);
+}
+
+
+static inline void
+lzma_sha256_finish(lzma_check_state *check)
+{
+	LZMA_SHA256FUNC(Final)(check->buffer.u8, &check->state.sha256);
+}
+
+#endif
+
 #endif